With the number of spells that you can prepare at a premium, I haven't found that it's a good idea to memorize both of these spells. You need slots for utility spells as well. Those enchantments won't dispel themselves, you know!
Really? you can prepare 1 spell per level which means 8 spells at level 8. There are very few useful spells to prepare in the 1st and 2nd level category, mainly utility spells. So you only need 1 or 2 of each of those. Then you prepare the most spells in levels 3 and 4 for the most choices at play time.
Seems like a no brainer. I mean there is literally no point in prepare a level 1 burning hands or magic missile when you can prepare a level 3 fireball or lightning bolt. Something like flaming sphere might get memorized every time, but that's just one slot.
I could see maybe grabbing one of these at levels 1 or 2:
1st-Fear, Charm Person, Disguise Self, Feather Fall, Grease, Identify
2nd-Darkvision, Flaming sphere,Hold Person, Invisibility, Knock, Mirror Image (if I wanted to off-tank), Scorching Burst (for use with a higher level slot).
At 3rd and 4th there isn't much to grab:
3rd-Blink, Fireball, Lightning Bolt, Slow, Stinking Cloud
4th-Evard's Tentacles, Polymorph, Wall of Fire
Some of those spells would be very optional like Charm Person, Feather Fall, Identify, Darkvision (if you aren't going anywhere dark), Knock (if there are no locks), Mirror Image (not wanting to off-tank, better than plate), Blink (if you have a tank in the party), Slow (only useful on some creatures, marginally useful on the rest).